Rubio calls Snowden scandal 'most damaging' espionage case in U.S. History. Is it?

Florida Sen. Marco Rubio makes it clear where he stands on Edward Snowden’s exposure of the National Security Agency’s spying programs: The situation couldn’t be more dire.

"The single most damaging revelation of American secrets in our history," Rubio said when asked about the matter after a foreign policy speech at the University of Texas on April 15.

"I can say to you unequivocally that there are Americans whose lives are at risk because of those disclosures," Rubio said, adding, "It’s been this massive revelation of all sorts of information about the way we operate to keep Americans safe delivered to potential adversaries, both the Russians and potentially the Chinese, done in the most damaging way possible and sprinkled with a bunch of lies."

There’s little question that the revelationsare nearly unprecedented in the history of American espionage.

Snowden, a former CIA employee, gave a small group of reportersthousands of classified documents he found with his security clearance as a contractor for the NSA. The information detailed surveillance programs and data mining operations against world leaders and American and European citizens. Facing espionage charges, he is now living in an undisclosed location in Russia.

Rubio’s commentsdid make us wonder whether there were other instances of espionage that would qualify as more wide-reaching than Snowden’s case. (Rubio’s office pointed us to an article in The Hillthat argued Snowden’s actions no doubt helped terrorists.) We can’t fact-check Rubio’s opinion on the situation, but we did survey a raft of historians and experts to see if they felt the senator was making a reasonable point.

The verdict: Reasonable, perhaps, but not definitive.

The many experts we spoke with had different opinions on the matter, and a lot depends on how you define "damaging." Read more from PolitiFact.